JP3547732B2 - Driving force control device for hybrid vehicle - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a hybrid vehicle in which an automatic transmission is arranged via a torque converter having a lock-up clutch between an engine and a motor / generator as power sources and a drive wheel between the engine and a motor / generator. The present invention relates to a driving force control device for a hybrid vehicle that controls a degree of engagement of a lock-up clutch.
[0002]
[Prior art]
Conventionally, an engine and a motor / generator are used as power sources, and a part of the running energy of a vehicle is converted into electric energy by the motor / generator and stored in a power storage device (so-called regenerative processing is performed) to improve fuel efficiency. There is something to plan. As a hybrid vehicle of this type, a hybrid vehicle in which a torque converter having a lock-up clutch is provided between a power source and a drive wheel, and the transmission efficiency of power between the power source and the drive wheel is adjusted by the lock-up clutch. is there.
[0003]
In performing the above-described regenerative processing, when the lock-up clutch is engaged with the motor generator, the traveling energy of the drive wheels can be directly transmitted to the motor generator. However, since torque fluctuations at the drive source are also transmitted directly to the drive wheels, noise, vibration, etc. are generated and drivability deteriorates. Therefore, it is important to control the engagement state of the lock-up clutch so as to obtain high regenerative efficiency while suppressing these.
[0004]
Therefore, there has been proposed an apparatus that performs a regenerative process by controlling the hydraulic pressure of a lock-up clutch so as to slide the drive source. For example, Japanese Patent Application Laid-Open No. 2000-170903 has means for controlling the engagement state of a lock-up clutch, and controls the engagement state (oil pressure) of the lock-up clutch by feedback so that the regeneration efficiency is maximized. Are disclosed.
[0005]
[Problems to be solved by the invention]
However, the hybrid vehicle has various running states (for example, whether or not the brake is operated, whether or not the cylinder is deactivated, etc.), and the amount of power that can be regenerated (the amount of regenerated power) differs depending on the running state. Therefore, when the running state is switched, the regeneration amount may fluctuate significantly. Since the degree of engagement (control oil pressure) of the lock-up clutch for obtaining this regenerative amount also fluctuates greatly, control of the oil pressure of the lock-up clutch by feedback control as described above can cause the large fluctuation to follow. It is difficult to control the hydraulic pressure of the lock-up clutch. For this reason, there has been a problem that the regeneration efficiency cannot be sufficiently increased.
[0006]
The present invention has been made in view of such circumstances, and a driving force control device for a hybrid vehicle that can control the hydraulic pressure of a lock-up clutch so that high regenerative efficiency can be obtained even when the running state changes. The purpose is to provide.
[0007]
[Means for Solving the Problems]
In order to solve the above problem, the invention described in claim 1 includes an engine (for example, an engine 2 in an embodiment described later) and a motor generator (for example, a motor generator 3 in an embodiment described later). A torque converter having a lock-up clutch (for example, a lock-up clutch 4 in an embodiment to be described later) between the power source and a drive wheel (for example, a drive wheel W in an embodiment to be described later) as a power source. For example, an automatic transmission (for example, an automatic transmission 6 in an embodiment described later) is provided via a torque converter 5 in an embodiment described later, and switching of a power source of a vehicle and a slip rate of a lock-up clutch are performed. Equipped with a control unit (for example, an ECU 13 in an embodiment described later) for controlling hydraulic pressure by hydraulic pressure. A driving force control device for a lid vehicle (for example, a driving force control device for a hybrid vehicle in an embodiment to be described later), wherein the control means performs target regeneration based on regeneration amount determination information obtained according to a traveling state of the vehicle. The required torque at the engine and the motor / generator end is calculated by retrieving the amount, adding the regenerative torque corresponding to the target regenerative amount to the friction torque searched by the friction torque information , and holding the required torque. Calculate the base oil pressure, control the oil pressure of the lock-up clutch to this base oil pressure, perform feedforward control to obtain the target slip rate of the lock-up clutch, and, based on the difference between the target slip rate and the actual slip rate, Driving force control device for hybrid vehicle, characterized in that feedback control of hydraulic pressure of lock-up clutch is performed. It is.
[0008]
According to the present invention, the target regeneration amount is searched by the regeneration amount determination information obtained according to the traveling state of the vehicle, so that even if the traveling state of the vehicle changes, high regeneration efficiency can be obtained. The quantity can be set. Then, since the required torque is obtained by adding the friction torque generated by the power source due to a change in the running state to the regenerative torque searched according to the running state of the vehicle, noise and vibration are suppressed to improve drivability. It is possible to obtain a torque that can obtain a required regenerative amount while maintaining the torque.
[0009]
Then, a base oil pressure for obtaining the necessary torque is calculated, and the base oil pressure is used to control the oil pressure of the lock-up clutch, so that feed-forward control for obtaining the target slip ratio of the lock-up clutch is performed. The lock-up clutch can be controlled so as to be in an appropriate engagement state. Further, even if the traveling state changes, an appropriate base hydraulic pressure can be obtained in accordance with the fluctuation. Since the target slip ratio of the lock-up clutch is subjected to feedforward control using the base hydraulic pressure, the target slip ratio can be controlled by making the base hydraulic pressure follow the fluctuation even when the running state changes.
[0010]
In addition, by performing feedback control of the hydraulic pressure of the lock-up clutch based on the difference between the target slip rate and the actual slip rate, it is possible to perform control to further increase the regenerative efficiency. Therefore, it is possible to control the oil pressure of the lock-up clutch so that high regenerative efficiency can be obtained even when the running state changes.
[0011]
Here, the regenerative amount determination information includes the remaining battery charge (SOC), the gear position (GP) of the automatic transmission, the presence or absence of the operation of the air conditioner, the engine speed, the brake operation status, and the like. Further, the friction torque information includes the presence / absence of cylinder deactivation, presence / absence of fuel cutoff (fuel cut), engine speed, presence / absence of operation of an air conditioner (load condition of the air conditioner), temperature of engine cooling water, and the like. In particular, it is preferable that the friction torque information includes a fuel cut during deceleration, a cylinder stop, and a load condition of the air conditioner.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a driving force control device for a hybrid vehicle according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram showing a driving force control device 1 for a hybrid vehicle according to an embodiment of the present invention.
[0013]
As shown in the figure, an engine 2 as a power source and a motor generator 3 are connected in series. An automatic transmission 6 is arranged between these power sources and the wheels W, W via a torque converter 5 having a lock-up clutch 4, and the automatic transmission 6 is connected to the power source. Further, a differential gear 8 is interposed between the automatic transmission 6 and the wheels W, W. The input side of the torque converter 5 is connected to the rotating shaft of the motor generator 3, and the output side of the torque converter 5 is connected to the input shaft 10 of the automatic transmission 6. Further, an oil pump 12 capable of supplying a control oil pressure for controlling the engagement state of the lock-up clutch 4 and an ECU 13 are provided.
[0014]
The torque converter 5 transmits torque via a fluid. The torque converter 5 includes a front cover 5a connected to the rotating shaft 9 of the motor / generator 3, a pump impeller 5b provided integrally therewith, and a pump impeller 5b between the front cover 5a and the pump impeller 5b. It is configured to include a turbine runner 5c that is arranged to face, and a stator 5d that is arranged between the pump impeller 5b and the turbine runner 5c.
[0015]
Further, a lock-up clutch 4 is provided between the turbine runner 5c and the front cover 5a so as to face the inner surface of the front cover 5a and can be engaged with the front cover 5a. The working oil is sealed in a container formed by the front cover 5a and the pump impeller 5b.
[0016]
The lock-up clutch 4 can be controlled to be engaged with the front cover 5a, and when the lock-up clutch 4 is disengaged (that is, disengaged), the pump impeller 5b is turned on by the front cover 5a. When rotated integrally with the shaft 5a, a helical flow of hydraulic oil is generated, and the helical flow of hydraulic oil acts on the turbine runner 5c to generate a rotational driving force, and a torque is applied to the output shaft 5e of the torque converter 5 via the hydraulic oil. Is transmitted.
When the lock-up clutch 4 is directly engaged, the rotational driving force is directly transmitted from the front cover 5a to the turbine runner 5c to the output shaft 5e without using the hydraulic oil.
[0017]
The degree of engagement of the lock-up clutch 4 is made variable by controlling the operating oil pressure of the lock-up clutch 4, and the rotation transmitted from the front cover 5 a to the turbine runner 5 c via the lock-up clutch 4. The driving force can be arbitrarily changed. The hydraulic pressure of the lockup clutch 4 can be controlled by a hydraulic circuit (not shown) provided between the lockup clutch 4 and the oil pump 12.
[0018]
The transmission 6 has a gear train (not shown) provided between the input shaft 10 and the output shaft 7 and capable of changing a speed ratio, and a clutch (not shown) for changing a power transmission gear of the gear train. Is provided with a hydraulic circuit (not shown) for operating the. The shift operation of the transmission 6 is executed by the ECU 13 controlling the hydraulic circuit and driving the clutch in accordance with, for example, a shift operation input from a driver or an operating state of the vehicle. The oil pump 12 is driven by power supply from a power storage device (not shown).
[0019]
As shown in FIG. 1, various sensors 21 to 28 are connected to the ECU 13, and based on information acquired by these sensors 21 to 28, switching of the power source of the vehicle and engagement of the lock-up clutch 4 are performed. The degree of matching can be controlled. In the present embodiment, an engine state detection sensor 21 for detecting a state of the engine 2 (presence or absence of cylinder deactivation, presence / absence of fuel cut), an accelerator pedal depression amount detection sensor 22, a brake operation detection sensor 23, A battery remaining capacity (SOC) detection sensor 24 to which regenerative power is charged, an air conditioner operation detection sensor 25, a hydraulic oil temperature detection sensor 26 that detects the hydraulic oil temperature of the lock-up clutch 4, and a gear of the automatic transmission 6. A shift stage detection sensor 27 for detecting a position (GP) and a slip ratio detection sensor 28 for detecting a torque converter slip ratio (ETR) are provided. In the present embodiment, the regenerative amount determination information for searching for the target regenerative amount by the sensors 21 to 28 and the friction torque information for searching for the friction torque are input to the ECU 13. This will be described later in detail.
[0020]
A case where regenerative braking is performed in the driving force control device 1 for a hybrid vehicle configured as described above will be described with reference to FIG. FIG. 2 is a main flow of the lock-up clutch 4 when regenerative braking is performed by the driving force control device 1 of FIG.
First, as shown in step S20 of the figure, it is determined whether or not the regeneration process can be performed (whether or not the regeneration is permitted). If the determination is "YES", the flow proceeds to step S30. If the determination result is "NO", the series of processing ends.
[0021]
If regeneration is permitted, a search for a target regeneration amount according to the running state of the vehicle is performed as shown in step S30. The search for the target regenerative amount is performed based on regenerative amount determination information, which will be described later in detail.
[0022]
Next, as shown in step S40, the regenerative torque corresponding to the target regenerative amount is searched, and the friction torque in the engine as the power source is searched, and the required torque is calculated by adding the friction torque to the regenerative torque. (The torque at the engine 2 and the motor / generator 3 end) is calculated. The search for the friction torque is performed based on the friction torque information described in detail later.
[0023]
Next, as shown in step S50, the base hydraulic pressure of the lock-up clutch 4 is calculated based on the required torque, and feedforward control is performed so that the hydraulic pressure of the lock-up clutch 4 becomes the base hydraulic pressure.
[0024]
Then, as shown in step S60, the hydraulic pressure of the lock-up clutch 4 is feedback-controlled based on the difference between the target slip rate (target ETR) and the actual slip rate (actual ETR), so that the lock-up clutch 4 Adjust the degree of engagement.
[0025]
Each process in the above-described main flow will be described in more detail with reference to FIGS. FIG. 3 is a sub-flow chart of the target regeneration amount search process in the ECU 13 shown in step S30 of FIG. In this process, regenerative amount determination information for searching for a target regenerative amount is input to the ECU 13 based on the information from the sensors 21 to 28 described above. That is, as shown in step S31, the ECU 13 inputs the regenerative amount determination information such as the gear position (GP) of the automatic transmission 6, the number of revolutions of the engine 2, the operation of the brake, and the operation of the air conditioner. The ECU 13 holds tables of regeneration amounts corresponding to the respective regeneration amount determination information, and reads out the target regeneration amounts from these tables as shown in step S32.
[0026]
As an example of this, FIG. 4 shows a case where the target regeneration amount is read from the table in the brake operating state, which is one of the regeneration amount determination information. FIG. 4A is a table showing the relationship between the engine speed when the brake is off and the corresponding regeneration amount, and FIG. 4B is a table showing the engine speed and the corresponding regeneration when the brake is on. It is a table which shows the relationship with quantity. These relationships are obtained for each gear position (GP), and lines A to D in FIG. 4 show a state where the gear positions are in the second to fifth speeds. FIG. 4A shows a case where the target regeneration amount is read from the input engine speed when the gear position is the fourth speed (line C). Similarly, tables corresponding to the other regeneration amount determination information are held, and a target regeneration amount corresponding to the input regeneration amount determination information is searched. In this way, an appropriate regeneration amount can be determined according to the traveling state.
[0027]
Next, the regenerative torque and the friction torque are searched. FIG. 5 is a sub-flow chart showing the regenerative torque and friction torque search processing shown in step S40 of FIG. In this process, friction torque information for searching for friction torque is input to the ECU 13 based on the information of the sensors 21 to 28 described above. That is, as shown in step S41, the ECU 13 inputs the engine speed, the presence or absence of cylinder deactivation, the presence or absence of fuel cut, the presence or absence of operation of the air conditioner, and the like, which are friction torque information. The ECU 13 holds a table of friction torque corresponding to each piece of friction torque information (see FIG. 6C). As shown in step S42, the ECU 13 reads the engine friction torque corresponding to the friction torque information from these tables. Read out. Then, the target regenerative amount (see FIG. 6A) obtained as described above is converted into a regenerative torque (see FIG. 6B), and the regenerative torque is applied to the engine as shown in step S43. The required torque is determined in consideration of the friction torque (see FIG. 6D).
[0028]
The processing of FIG. 5 described above will be described with reference to FIG. FIG. 6A is a table showing the relationship between the engine speed and the regenerative amount for each gear position, and FIG. 6B is a table in which the regenerative amount is converted into regenerative torque. In these figures, lines A to D correspond to the case where the gear position is in the second to fifth gears. In the present embodiment, the line C when the gear position is the fourth speed is searched as the regenerative torque.
[0029]
FIG. 6C is a table showing the relationship between the engine speed and the engine friction torque corresponding to the presence or absence of cylinder deactivation, which is one of the friction torque information. In the figure, a line E indicates a case where cylinder deactivation is performed, and a line F indicates a case where cylinder deactivation is not performed. FIG. 6D is a table showing the relationship between the engine speed and the required torque. The required torque is obtained by adding the friction torque of FIG. 6C to the regenerative torque of FIG. A line G in FIG. 6D shows a case where the gear position is in the fourth speed (line C in FIG. 6B) and a case where the cylinder is not deactivated (line F in FIG. 6C). ing. In this way, noise and vibration can be suppressed to maintain good drivability, and a torque that can provide a required amount of regeneration can be obtained. Similarly, for other pieces of friction torque information, tables corresponding to the respective pieces of friction torque information are held, and a friction torque suitable for a running state can be determined from these tables.
[0030]
Next, the base hydraulic pressure of the lock-up clutch 4 is searched. FIG. 7 is a sub-flow chart showing a search process of the base oil pressure of the lock-up clutch (L / C) 4 of FIG. In step S51 in FIG. 8, the required torque (the torque at the end of the engine 2 and the motor / generator 3) is determined as α, as shown in FIG. When obtaining the base oil pressure of the lock-up clutch 4 from this α, the correction is made as the correction term H in consideration of the change due to the degree of engagement of the lock-up clutch 4 (slip ratio that changes depending on the gear position and the vehicle speed). By performing this correction, the target torque capacity of the lock-up clutch 4 becomes α ′.
[0031]
Then, as shown in step S52, a base oil pressure corresponding to the target torque capacity α 'is searched from FIG. FIG. 8 is a table showing the relationship between the target torque capacity and the base oil pressure. In this table, lines I to K correspond to the cases where the temperature of the hydraulic oil is 60 degrees, 70 degrees, and 80 degrees. FIG. 7 shows a case where the base oil pressure β is calculated from the target torque capacity α ′ in the line I where the temperature of the hydraulic oil is 60 degrees. The hydraulic pressure of the lock-up clutch 4 is subjected to feedforward control based on the calculated base hydraulic pressure.
[0032]
Thus, the lock-up clutch 4 can be controlled so as to be in an appropriate engagement state according to the traveling state. Further, even if the running state changes, a base oil pressure corresponding thereto is obtained, and the lock-up clutch 4 is controlled by this base oil pressure. Hydraulic pressure can be controlled.
[0033]
Then, as described below, the hydraulic pressure of the lock-up clutch 4 is feedback-controlled. FIG. 9 is a sub-flow chart showing the feedback control processing of the lock-up clutch 4 shown in step S60 of FIG. FIG. 10 is a block diagram showing the processing contents of FIG. In the present embodiment, the feedback control is performed based on a torque converter slip ratio (ETR). This slip ratio is defined as in the following equation (1).
[0034]
Formula (1): ETR = Ns / Ne
[0035]
Here, Ns is the rotation speed of the input shaft 10, and Ne is the rotation speed of the rotation shaft 9 of the engine 2. In performing the slip control, a target slip rate is calculated, and a difference from an actual slip rate is obtained. Then, as shown in step S61 of FIG. 9, a difference between the target slip ratio and the actual slip ratio is obtained, and PI (proportional or integral) control is performed. That is, as shown in step S61, a value obtained by multiplying the difference between the target slip rate and the actual slip rate by the PI gain is used as the feedback term. Then, as shown in step S62, the sum of the base oil pressure of the lock-up clutch 4 and the feedback term is set as the oil pressure command value of the lock-up clutch 4. Thereby, the control accuracy of the lock-up clutch 4 can be increased so that higher regenerative efficiency can be obtained. Before the feedback control process is performed, the hydraulic pressure of the lock-up clutch 4 is subjected to feedforward control, so that the control in the feedback control requires relatively fine adjustment. Therefore, unlike the related art, even when the running state changes, appropriate control can be performed following the change. In the embodiment, the PI control is used. However, the present invention is not limited to this. The control may be changed to P (proportional) control or PID (proportional, integral, differential) control as needed.
[0036]
As described above, in the driving force control device for a hybrid vehicle according to the present embodiment, the hydraulic pressure of the lock-up clutch can be controlled so that high regenerative efficiency can be obtained even when the running state changes. Note that the content of the present invention is not limited to the embodiment. For example, the automatic transmission may be an AT (stepped transmission) or a CVT (stepless transmission).
[0037]
【The invention's effect】
According to the first and second aspects of the present invention, the regenerative amount can be set so that high regenerative efficiency can be obtained even when the running state of the vehicle changes. Further, it is possible to obtain a torque that can obtain a required regeneration amount while suppressing noise and vibration and maintaining good drivability. Then, the lock-up clutch can be controlled so as to be in an appropriate engagement state according to the running state, and the lock-up clutch can sufficiently follow the change in the running state. In addition, by performing feedback control, control accuracy can be further increased. Therefore, it is possible to control the oil pressure of the lock-up clutch so that high regenerative efficiency can be obtained even when the running state changes.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a driving force control device for a hybrid vehicle according to an embodiment of the present invention.
FIG. 2 is a main flowchart showing control of a lock-up clutch when performing regenerative braking in the driving force control device of FIG. 1;
FIG. 3 is a sub-flow chart showing a target regeneration amount search process of FIG. 2;
FIG. 4 is a table used in the processing steps of FIG. 3;
FIG. 5 is a process diagram showing a sub-flow showing a friction torque search process during regeneration in FIG. 2;
FIG. 6 is a table used in the processing steps of FIG. 4;
FIG. 7 is a sub-flow chart showing a search process of a base oil pressure applied to the lock-up clutch of FIG. 2;
FIG. 8 is a table used in the processing steps of FIG. 7;
FIG. 9 is a sub-flow chart showing a lock-up clutch slip feedback control process of FIG. 2;
FIG. 10 is a block diagram illustrating a control process of FIG. 9;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Driving force control device of hybrid vehicle 2 Engine 3 Motor / generator 4 Lock-up clutch (L / C clutch)
5 Torque converter 6 Transmission 7 Output shaft 12 Oil pump 13 ECU

Claims (2)

An automatic transmission is provided between the power source and the drive wheels via a torque converter having a lock-up clutch, which uses an engine and a motor / generator as power sources. A driving force control device for a hybrid vehicle including a control unit for controlling a slip ratio by hydraulic pressure,
The control means,
Search for the target regeneration amount by the regeneration amount determination information obtained according to the traveling state of the vehicle,
In consideration of the friction torque searched by the friction torque information to the regenerative torque corresponding to the target regenerative amount , the necessary torque at the engine and the motor / generator end is calculated,
Calculate a base oil pressure capable of holding the required torque, control the oil pressure of the lock-up clutch to this base oil pressure, and perform feedforward control to obtain a target slip ratio of the lock-up clutch,
A driving force control device for a hybrid vehicle, wherein feedback control of a hydraulic pressure of a lock-up clutch is performed based on a difference between a target slip ratio and an actual slip ratio. The driving force control device for a hybrid vehicle according to claim 1, wherein the friction torque information includes a fuel cut during deceleration, a cylinder deactivation, and a load condition of an air conditioner.

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